Cretaceous "mammal-toothed" lizard found in Mexico

Adam Khor

It belonged to genus Peneteious within family Teiidae, which still has living members. However, it was unique because its teeth had several cusps, like mammal teeth, something extremely unusual in lizards.
The 72 million year old fossil was so small that was only identified using a microscope. It was found in Coahuila, Mexico (first time this genus is found in this country- it was already known from Montana, Utah and Texas). The article (in Spanish) does provide a brief description of what the lizard would look like- 7 to 70 cms long, flat body, four toes in each foot- and its infered behavior- an aggressive carnivore-, but it seems more like a general description of the Teiidae family rather than Peneteious itself.

The best known members of family Teiidae today are the Tegu, sometimes nicknamed "South American Monitors":

The family is also notorious for including some completely parthenogenetic, all female species.

Galvasean

A lot of interesting finds coming out of Mexico these days..

Adam Khor

Here's the actual fossil: